Tobacco and cigarette giving decreased sub-current smoke

ABSTRACT

Tobacco preferably contains powdery basic calcium phosphate, particularly, powdery calcium-defective basic calcium phosphate, adsorbed on or mixed with the tobacco, for decreasing the amount of side stream smoke rising from the burning site. In the case that tobacco is used in the form of a cigarette, the paper sheet surrounding the tobacco may contain powdery basic calcium phosphate.

FIELD OF THE INVENTION

[0001] The present invention relates to a tobacco and cigarette giving decreased sub-current smoke and reducing harmful tar and heavy metal contaminants in the main current smoke as well as sub-current smoke.

BACKGROUND OF THE INVENTION

[0002] The smoke emitting from the burning tobacco or cigarette is classified into a main current smoke which is absorbed by the smoker and a sub-current (side-stream) smoke which rises from the burning site.

[0003] Mutation Research, 222(1989), 73-80, and Environ. Sci. Technol. 23(1989), 679-687 report that harmful materials such as tar and heavy metals are contained in larger amounts in the sub-current smoke than in the main current smoke. It is known that the sub-current smoke causes passive smoking.

[0004] For trapping tar and heavy metal contaminants in the main current smoke, a filter containing charcoal is effective and is widely employed. However, no effective means have been developed for trapping the tar and heavy metal contaminants in the sub-current smoke.

SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to provide mild-tasted tobacco and cigarette which produce less sub-current smoke, and further decrease a heavy metal content not only in the main current smoke but also in the sub-current smoke, while keeping good taste and aroma of the fresh tobacco and cigarette.

[0006] The invention resides in tobacco having powdery basic calcium phosphate adsorbed thereon or mixed therewith.

[0007] The invention further resides in a cigarette comprising tobacco and a paper sheet surrounding the tobacco, in which the tobacco has powdery basic calcium phosphate adsorbed thereon or mixed therewith.

[0008] The invention furthermore resides in a cigarette comprising tobacco and a paper sheet surrounding the tobacco, in which the paper sheet contains powdery basic calcium phosphate therein.

DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention is described below in more detail.

[0010] The powdery basic calcium phosphate employed in the invention preferably has a specific surface area (in terms of BET specific surface area) in the range of 10 to 150 m²/g, more preferably 50 to 120 m²/g, most preferably 70 to 120 m²/g, so that the powder can have a high activity, and preferably has a mean particle size of 0.005 to 100 μm. The powdery basic calcium phosphate may be in a granular form in which a powdery phosphate is aggregated.

[0011] If the tobacco is produced in the form of a cigarette, the paper sheet surrounding the tobacco can contain the powdery basic calcium phosphate.

[0012] The powdery basic calcium phosphate is calcium phosphate containing a base group (such as hydroxyl group), and is generally referred to as hydroxyapatite, which can be expressed by the formula of Ca₁₀(PO₄)₆(OH)₂.

[0013] The powdery basic calcium phosphate preferably is powdery calcium-defective basic calcium phosphate, which can be expressed by the formula of Ca_(10-x)H_(2x)(PO₄)₆(OH)₂, in which x is a number of 0.01 to 2. The calcium-defective basic calcium phosphate is generally referred to as ACP, that is, amorphous calcium phosphate. The calcium-defective basic calcium phosphate can be produced by modifying the known process for the production of ordinary basic calcium phosphate in such manner that the reaction is conducted using calcium in an amount less than the stoichiometrically equivalent amount, at a relatively low temperature for a shortened period of time.

[0014] The tobacco of the invention may further contain other adsorbing powdery material such as a powder of calcium tertiary phosphate, clay, silica, alumina, calcia, magnesia, glass, and gypsum. The other powdery material is adsorbed on or mixed with the tobacco.

[0015] The calcium tertiary phosphate is expressed by the formula of Ca₃(PO₄)₂. The calcium tertiary phosphate can be of α-type or β-type, any of which has good affinity to the tobacco and the basic calcium phosphate. Tar and heavy metal contaminants are easily adsorbed by the calcium tertiary phosphate.

[0016] The clay contains chemical components of SiO₂, Al₂O₃, H₂O, and/or MgO and is in the form of fine particles. Therefore, the clay has good affinity to the tobacco and the basic calcium phosphate. Tar and heavy metal contaminants are easily adsorbed by the clay. The H₂O contained in the clay evaporates while the tobacco is burning. Such evaporation causes endothermic reaction and may accelerate the adsorption of tar and heavy metal contaminants by the clay.

[0017] Gypsum contains two waters of crystallization in one molecule and releases the water when it is heated. Such water release causes endothermic reaction and may accelerate the adsorption of tar and heavy metal contaminants by the clay.

[0018] Non-crystalline oxides such as silica, alumina, calcia, and magnesia have a relatively large surface area. Accordingly, tar and heavy metal contaminants are easily adsorbed by these non-crystalline oxides. Glass powder such as silicate glass powder also has a relatively large surface area.

[0019] The basic calcium phosphate and other adsorbents can be attached to the tobacco or paper sheet of the cigarette, for example, by spraying an aqueous dispersion of the basic calcium phosphate powder and other powdery adsorbents on the tobacco or the paper sheet or simply mixing them with the tobacco. Otherwise, the basic calcium phosphate powder can be formed to give a thin paper film and attached to the paper sheet of cigarette.

[0020] The basic calcium phosphate is preferably employed in an amount of 0.1 to 50 wt. %, more preferably 0.1 to 30 wt. %, per the amount of the tobacco or the paper sheet.

[0021] Other absorbent is preferably employed in an amount of 0.1 to 50 wt. %, more preferably 0.1 to 30 wt. %, per the amount of the tobacco or the paper sheet.

[0022] In the case of cigarette, the filter attached to the cigarette preferably contains the basic calcium phosphate, preferably in combination with other adsorbents such as a powder of calcium tertiary phosphate, clay, silica, alumina, calcia, magnesia, glass, or gypsum.

[0023] The adsorbent can be zeolite or tourmaline.

[0024] The present invention is further described by the following examples.

EXAMPLE 1

[0025] Evaluation of production of cub-current rising from cigarette and variation of taste and aroma of cigarette

[0026] (1) Commercially available cigarettes (Peace, Hi-lite, and Seven Star, trademarks of Japan Tobacco Co., Ltd.) were broken to collect the tobacco powder and the paper sheet separately. With some of the tobacco powders were mixed a adsorbent mixture of powdery basic calcium phosphate (specific surface area: 80 m²/g) and clay (weight ratio: 10:1) in an amount of 10 wt. %. To some of the paper sheets were sprayed an aqueous dispersion containing the adsorbent mixture of powdery basic calcium phosphate and clay (10:1).

[0027] Then, new cigarettes (No. 1 to No. 9) were produced using thus treated tobacco powder and untreated paper sheet, thus treated tobacco powder and thus treated paper sheet, or untreated tobacco powder and thus treated paper sheet. To the produced cigarette was attached a commercially available tobacco filter. The produced new cigarettes are numbered as follows:

[0028] [Peace]

[0029] No.1: adsorbent mixture was mixed with tobacco

[0030] No.2: adsorbent mixture was sprayed on paper sheet

[0031] No.3: adsorbent mixture was mixed with tobacco and sprayed on paper sheet

[0032] [Hi-lite]

[0033] No.4: adsorbent mixture was mixed with tobacco

[0034] No.5: adsorbent mixture was sprayed on paper sheet

[0035] No.6: adsorbent mixture was mixed with tobacco and sprayed on paper sheet

[0036] [Seven Star]

[0037] No.7: adsorbent mixture was mixed with tobacco

[0038] No.8: adsorbent mixture was sprayed on paper sheet

[0039] No.9: adsorbent mixture was mixed with tobacco and sprayed on paper sheet

[0040] A panel composed of twenty adults (males and females) were asked to smoke the above-mentioned commercially available cigarettes and the sample cigarettes (No. 1 to No. 9) for evaluating production of sub-current smoke, taste and aroma of the sample cigarettes in comparison with the corresponding commercially available fresh cigarettes.

[0041] The results are given in Table 1 in which AA means that sub-current smoke prominently decreases and BB means that sub-current smoke somewhat decreases. The number of persons giving favorable opinion on taste and aroma means number among the panel (20 adults). TABLE 1 Number of persons giv- Sample Production of ing favorable opinion Number sub-current smoke on taste and aroma No. 1 AA 18 No. 2 BB 14 No. 3 AA 12 No. 4 AA 16 No. 5 BB 18 No. 6 AA 12 No. 7 AA 17 No. 8 BB 19 No. 9 AA 14

[0042] The results set forth in Table 1 indicate that the cigarettes according to the invention (No. 1 to No. 9) produce less amount of sub-current smoke, as compared with the corresponding commercially available cigarettes. There was noted little difference on the taste and aroma between the cigarettes (No. 1 to No. 9) and the corresponding commercially available cigarettes.

EXAMPLE 2

[0043] Measurements of tar and heavy metal contaminants in sub-current smoke rising from cigarette

[0044] The commercially available cigarettes, namely, Peace, Hi-Lite, and Seven Star were broken to collect tobacco, paper sheet, and a filter, separately. The paper sheet was cut to give pieces of less than 5 mm×5 mm.

[0045] Each of a mixture of the tobacco and paper sheet was mixed with a powdery hydroxyapatite (i.e., basic calcium phosphate) (Ordinary HA: specific surface area 80 m²/g, or Ca defective HA: specific surface area 90 m²/g) and optionally an auxiliary adsorbent, that is, clay, calcia, magnesia or gypsum, in the manner set forth in Table 2. TABLE 2 Sample Mixing ratio (weight ratio) Number Tobacco & paper Basic Ca phosphate Other [Peace] No. 10 50 50(Ordinary HA) — No. 11 50 50(Ca defective HA) — No. 12 90 10(Ordinary HA) — No. 13 90 10(Ca defective HA) — No. 14 90  8(Ca defective HA) 2(clay) No. 15 90  8(Ca defective HA) 2(calcia) No. 16 90  8(Ca defective HA) 2(magnesia) No. 17 90  8(Ca defective HA) 2(calcia) [Hi-Lite] No. 18 50 50(Ca defective HA) — [Seven Star] No. 19 50 50(Ca defective HA) —

[0046] For preparing each sample, 50 commercially available cigarettes were broken.

[0047] The sample was placed in a quartz tube and heated to 800° C. Smoke rising from the sample was collected in alcohol. The alcohol was subjected to gas chromatography (G-3000 type gas chromatograph, available from Hitachi Limited) for determining the amount of tar collected in the alcohol using a hydrogen flame ionizing detector (FID). Cadmium and lead were analyzed by means of ICP. As a control, a fresh cigarette, such as Peace, Hi-Lite, or Seven Star was utilized. The results are set forth in Table 3. The amount of tar set forth is a relative value, based on the amount detected from the fresh cigarette.

[0048] For evaluating the cigarettes treated with the hydroxyapatite in their taste and aroma, a panel of ten adults was asked to smoke for comparing the fresh cigarette and the treated cigarette. The number set forth in Table 3 represents the number who stated that the taste was made mild, while the good aroma was kept. TABLE 3 Sample Tar Cd Pb Taste & Aroma Number (wt. %) (ppm) (ppm) (persons) [Peace] No. 10 40 no trace no trace 7 No. 11 30 no trace no trace 8 No. 12 60 no trace no trace 10 No. 13 55 no trace no trace 10 No. 14 40 no trace no trace 9 No. 15 30 no trace no trace 10 No. 16 35 no trace no trace 9 No. 17 30 no trace no trace 9 Control 100 >0.01 >0.01 — [Hi-Lite] No. 18 35 no trace no trace 9 Control 100 >0.01 >0.01 — [Seven Star] No. 19 30 no trace no trace 10 Control 100 >0.01 >0.01 —

[0049] The samples according to the invention gave smoke containing almost no heavy metal contaminants and a less amount of tar, while keeping or enhancing the good taste and aroma of the fresh cigarette.

[0050] Analysis of tars collected from the sample cigarettes indicated that the amounts of tar components having a relatively high molecular weight such as biphenyline, fluorene, anthracene, fluorancene, ethyl 1,2-benzene-2-carboxylate, and benzpyrene particularly decreased. Particularly, the amount of the so-called cancer inducing compounds such as benzpyrene and fluorancene decreased.

[0051] Further, it was noted that the basic calcium phosphate made the taste of cigarette milder.

[0052] Furthermore, it was noted that the sub-current smoke rising from the sample cigarette according to the invention was less than that rising from the untreated fresh cigarette.

EXAMPLE 3

[0053] The commercially available cigarette, namely, Peace, was broken to collect tobacco powder. On the collected tobacco powder was sprayed an aqueous dispersion of basic calcium phosphate in an amount of 3 weight parts per 10 weight parts of the tobacco powder. Thus treated tobacco powder was then covered with a paper sheet to give a sample cigarette (No. 20).

[0054] A panel composed of 10 adults was asked to smoke the sample cigarette No. 20 as well as the corresponding fresh cigarette for comparing the taste and aroma. All member confirmed that there ware no change on the taste and aroma. Further, it was confirmed that the sub-current smoke was reduced. It was also noted that light of the sample cigarette went out within one or two minutes after the smoking was stopped. 

What is claimed is:
 1. Tobacco having powdery basic calcium phosphate adsorbed thereon or mixed therewith.
 2. The tobacco of claim 1, in which the powdery basic calcium phosphate is powdery calcium-defective basic calcium phosphate.
 3. The tobacco of claim 1, in which the powdery basic calcium phosphate has a specific surface area in the range of 10 to 150 m²/g.
 4. The tobacco of claim 1, in which a powder of material selected from the group consisting of calcium tertiary phosphate, clay, silica, alumina, calcia, magnesia, glass, and gypsum is further adsorbed on or mixed with the tobacco.
 5. A cigarette comprising tobacco and a paper sheet surrounding the tobacco, in which the tobacco has powdery basic calcium phosphate adsorbed thereon or mixed therewith.
 6. The cigarette of claim 5, in which the powdery basic calcium phosphate is powdery calcium-defective basic calcium phosphate.
 7. The cigarette of claim 5, in which the powdery basic calcium phosphate has a specific surface area in the range of 10 to 150 m²/g.
 8. The cigarette of claim 5, in which a powder of material selected from the group consisting of calcium tertiary phosphate, clay, silica, alumina, calcia, magnesia, glass, and gypsum is further adsorbed on or mixed with the tobacco.
 9. A cigarette comprising tobacco and a paper sheet surrounding the tobacco, in which the paper sheet contains powdery basic calcium phosphate therein.
 10. The cigarette of claim 9, in which the powdery basic calcium phosphate is powdery calcium-defective basic calcium phosphate.
 11. The cigarette of claim 9, in which the powdery basic calcium phosphate has a specific surface area in the range of 10 to 150 m²/g. 